Liaison statement
Control plane resilience
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State | Posted |
---|---|
Submitted Date | 2005-11-25 |
From Group | ITU-T-SG-15 |
From Contact | Hiroshi Ota |
To Group | ccamp |
To Contacts | kireeti@juniper.net; adrian@olddog.co.uk |
Cc | sob@harvard.edu fenner@research.att.com zinin@psg.com ccamp@ops.ietf.org maeda@ansl.ntt.co.jp sjtrowbridge@lucent.com |
Response Contact | tsbsg15@itu.int greg.jones@itu.int |
Technical Contact | hklam@lucent.com betts01@nortel.com |
Purpose | For information |
Attachments |
Control plane resilience
ITU-T Rec. G.8080/Y.1304 (2001) Amendment 2 (02/05) |
Body |
At the recent Q12/15 and Q14/15 Rapporteur meeting, it was reported that CCAMP is discussing the issue of control plane resilience. This topic has been considered in the development of ASON Recommendations in SG15 and we would like to draw to your attention some of this work that may be helpful to CCAMP. G.8080 Section 12 discusses resilience by describing principles to follow, and Appendix II describes resilience in terms of pair-wise relationships between planes/components. Resilience refers to the ability of the control plane to continue operating under failure conditions. These may occur as a result of disruption of communication between control plane components (e.g., SCN failure) or failure of control plane components themselves. When communication between the control plane and transport (bearer) plane becomes available, four principles apply (from G.8080): 1. The control plane relies on the transport plane for information about transport plane resources. 2. Consistency between the control plane view and the corresponding transport network element is established first (vertical consistency). 3. Once local consistency is established, horizontal consistency is attempted. Here, control plane components synchronize with their adjacent components. This is used to re-establish a consistent view of routing, call, and connection state. 4. Existing connections in the transport plane are not altered if the control plane fails and/or recovers. Control plane components are therefore dependent on transport state (existing cross connections). Note that the transport plane in G.8080 refers to G.805 layer networks, which includes connection-oriented packet layers such as ATM. Attachment: <ITU-T G.8080 Amendment 2> : http://www.itu.int/rec/recommendation.asp?type=items&lang=e&parent=T-REC-G.8080-200502-I!Amd2 |